As one of processes of manufacturing a semiconductor device, in some cases, a process of forming a thin film such as a silicon nitride film or a silicon oxide film on a substrate may be performed, for example, by supplying a precursor gas containing silicon, a nitriding gas, an oxidizing gas or the like to the substrate.
When the thin film as described above is formed on the substrate, it is possible to improve a resistance to wet etching, for example, by allowing the thin film to contain carbon or the like. At this time, if the carbon can be contained at a high concentration by controlling a concentration of carbon in the thin film with high precision, it is possible to further improve an etching resistance of the film.